1. Field of the invention
The present invention relates to method of fabricating a tape for tape rule, and more particularly, to a method in which a colored polyester film is coated on both surfaces of a steel tape as base coat thereby forming a non-poisonous, environment-conscious and low cost tape for tape rule.
2. Description of the Prior Art
FIG. 1 shows a fundamental flow chart illustrating a conventional method of fabricating a tape for tape rule, the fabricating steps are:
1. Preparing a roll of originally colored metallic tape 11;
2. Forming a base coat layer by adhering aluminum foil or baking paint on both tape surfaces 12;
3. Printing graduations on the tape which already having being finished base coating 13;
4. Coating a polyester film 14 on both tape surfaces after printing graduations 13;
5. Trimming and burling flashes of the aluminum foil and the polyester film 15; and
6. Finishing a tape product 16.
In the conventional fabricating method generally adopted by manufactures, the paint used as base coat induces a serious problem. As it is well known, any colored painting materials usually contain poisonous chemical compounds with heavy metals and a stimulating odor not only harmful to manufacturing personnel who constantly contact it, but also air polluting. The product of a tape rule made as such is possibly harmful and is by no means a good product.
Except making procedure is complicated. Foams are too apt to be produced between the aluminum foil and the polyester film as the two are not so compatible to attract firmly with each other thereby reducing yield of the tape fabrication that leads to a waste of production cost. Besides, owing to rather large thickness of aluminum foil, the thickness of steel sheet used to form the tape body must be reduced as thin as possible with the result that the finished tape product is in lack of stiffness and flexibility as well.
Furthermore, no matter whether the base coat is formed of aluminum foil or of baked paint, both require a considerably high fabrication cost, as a result, users have to pay a higher price to purchase a tape rule whose tape is formed as such.
In order to overcome the shortcomings inherent to the conventional technique described above, the present inventor has delved into this matter with a long time efforts and came to realization of the present invention.
It is an object of the present invention to provide method of fabricating a nonpoisonous tape for tape rule.
It is another object of the present invention to provide method of fabricating a tape having proper stiffness, flatness and flexibility, for tape rule.
It is still another object of the present invention to provide method of fabricating a tape with a good color rendering, and easy for observing its graduations thereon for measurement.
The above mentioned objects and other advantages of the present invention will be achieved by the method of fabricating a tape for tape rule comprising the steps of:
1. Adding a dyestuff into a polyester material mixed with a binding glue and churning the. mixture so as to offer the polyester material a specified color.
2. Adhering the colored polyester prepared in step 1 by rolling with a roller which is maintained at a constant temperature of 150xc2x0 C., to both surfaces of the tape so as to form a colored base coat of the tape.
3. Printing graduations on a surface (or both surfaces) of the tape and then carrying out infrared drying.
4. Rolling a mixture of a transparent polyester and a binding glue with a roller maintained at a constant temperature of 150xc2x0 C. on the tape, to form a polyester protecting layer on both tape surfaces.
5. Finishing fabrication of a polyester film coated tape for tape rule.
The base coat formed in step 2 makes the finished tape non-poisonous and environment-conscious. In addition, the polyester film of the present invention is thinner than the aluminum foil or the baked paint formed by conventional techniques, consequently, a thicker steel strip can be used to form the tape which results in upgrading stiffness and flexibility of the finished tape.